The present invention relates to open end wrenches, and more particularly to an improved structure of open end wrench which is practial for grasping and turning normal bolts and nuts of different specifications as well as worn-out bolts and nuts of different specifications.
An open end wrench is handy tool intensively used for grasping and turning bolts and nuts. A variety of open end wrenches have been disclosed having teeth, raised portions or rough grasping faces at the jaws for grasping and turning normal bolts and nuts as well as worn-out bolts and nuts. Exemplars of conventional open end wrenches are shown in FIGS. from 1 to 13. The open end wrench shown in FIGS. 1, 2, and 3 has two flat raised portions at the jaws. This structure of open end wrench is functional for turning normal bolts and nuts as well as slightly worn-out bolts and nuts. However, it can not positively grasp and turn excessively worn-out bolts and nuts. FIGS. 4, 5, 7,8, 9, 10 and 11 show other different designs. These designs can grasp and turn bolts and nuts of different sizes. However, these designs can not positively grasp and turn excessively worn-out bolts and nuts. FIG. 6 shows another design of open end wrench which is similar to the open end wrench shown in FIGS. 1 to 3. FIG. 12 shows an open end wrench having rough faces at the jaws. FIG. 13 shows an open end wrench having teeth at the jaws. The open end wrenches shown in FIGS. 12 and 13 can positively grasp and turn normal bolts and nuts, however they tend to slip when turning an excessively worn-out bolt or nut.
It is one object of the present invention to provide an open end wrench which is practical for grasping and turning hexagon head bolts and hexagon nuts as well as square head bolts and square nuts. It is another object of the present invention to provide an open end wrench which is practical for grasping and turning normal bolts and nuts of different specifications as well as worn-out bolts and nuts of different specifications. According to the present invention, the open end wrench comprises a mouth defined between two jaws and nest thereof, a flat raised portion and a longitudinal series of teeth respectively raised from the two jaws inside the mouth, the longitudinal series of teeth including an odd number of teeth, the length of the flat raised portion being equal to the distance between the mid point of the first tooth of the longitudinal series of teeth and the midpoint of the last tooth thereof, the total length of the longitudinal series of teeth being equal to 0.67 of the width of the mouth, the distance from the remote end of the longitudinal series of teeth to the nest being 0.91 of the width of the mouth, the first tooth of the longitudinal series of teeth and the second tooth thereof having a respective smoothly curved peak for grasping normal square head bolts and square nuts and normal hexagon head bolts and hexagon nuts, the third tooth and the fourth tooth of the longitudinal series of teeth being pointed teeth, the distance between the mid point of the flat raised portion and the third tooth of the longitudinal series of teeth being equal to the width of the mouth, the fifth tooth of the longitudinal series of teeth being for turning hexagon head bolts, hexagon nuts, square head bots and square nuts in the reversed direction.